Method of and apparatus for gun firing practice



Filed Feb. 24, 1964 Feb. 21, 1967 KAHN 3,304,846

METHOD OF AND APPARATUS FOR GUN FIRING PRACTICE 4 Sheets-Sheet 1 Feb. 21, 1967 1. KAHN 3,304,846

METHOD OF AND APPARATUS FOR GUN FIRING PRACTICE Filed Feb. 24, 1964 4 Sheets-Sheet 2 Feb. 21, 1967 KAHN 3,304,846

METHOD OF AND APPARATUS FOR GUN FIRING PRACTICE Filed Feb. 24, 1964 4 Sheets-Sheet 5 Feb. 21, 1967 l. KAHN 3,304,846

METHOD OF AND APPARATUS FOR GUN FIRING PRACTICE Filed Feb. 24, 1964 4 Sheets-Sheet 1 F600 L F500 R FIG- 5a BNn 51.21 09000 BNLSLZI 09000 G- 5 FIGS- 3,304,846 Patented Feb. 21, 1967 3,304,846 METHOD OF AND APPARATUS FOR GUN FIRING PRACTICE Iwan Kahn, Wallisellen, Switzerland, assignor to Contraves AG, Zurich, Switzerland Filed Feb. 24, 1964, Ser. No. 346,691 Claims priority, application Switzerland, Feb. 22, 1963, 2,251/63 14 Claims. (Cl. 95-1) The present invention concerns in the first place surveying apparatus adapted to furnish directional data of remote objects in terms of polar coordinates in a polar coordinate system. More particularly, the inventionconcerns a surveying apparatus of this type and being constructed so that it is particularly useful as a means of observation at gun firing practice. In the second place, the invention concerns a method of observation at gun firing practice involving a target practice object.

In the field of gun firing practice substantial difficulties exist in carrying out the necessary observation for determining the accuracy of firing and particularly the accuracy of aiming the gun at the practice target and the accuracy of the computation of the data determining the aiming of the gun. Particularly inconveniences exist as far as gun firing practice is concerned which involves moving targets at sea.

Conventionally gun firing practice at sea is carried out by having a target ship towed by a tug or the like and by shooting either from a stationary gun on land or from a moving vessel at the target ship.

Against this background it is one object of this invention to provide for a method of observation at gun firing practice which is considerably simpler and more economical than the conventional system.

.It is another object of this invention to provide for a method of observation at gun firing practice involving two vessels at sea and avoiding the need of a tug or the like for towing a target vessel or ship.

It is still another object of this invention to provide for a method of the type set forth in which both vessels may function as practice vessels and as target vessels.

It is another object of this invention to provide for ob servation apparatus specifically suitable for carrying out the above described methods.

It will be seen from the following description of the invention that it is possible to have two navy vessels carry out gun firing practice by using each other mutually as targets. Of course, this entails the necessity of having at least one of the ships, preferably both, equipped with observation or surveying apparatus according to the invention. In this case both ships may fire alternatingly, may steer any desired course and use any desired speeds so that the gun firing practice can be carried out with much greater efficiency than heretofore because the situations occurring in warfare may be closed imitated.

With above objects in View, the invention includes a method of observation at gun firing practice involving a target practice object, comprising the steps of: aiming a gun for shooting in a direction and a distance computed to hit an imaginary target point located in an imaginary target direction offset horizontally and laterally a predetermined angle in one predetermined sense with respect to the line of sight from the gun position to said target practice object; firing the gun; and observing simultaneously and superimposed upon each other an image of said target practice object taken along said line of sight and an image of the area of said imaginary target point taken along said imaginary target direction, whereby observation of the superimposed images shows the location of a projectile fired at said imaginary target point relative to the target practice object in the same manner as if the projectile had been fired at the target practice object proper.

In another aspect of the invention it includes a surveying apparatus comprising, in combination, a first surveying means for furnishing directional data of a remote object in terms of polar coordinates in a first polar coordinate system; and a second surveying means for furnishing directional data of a remote object in terms of polar coordinates in a second polar coordinate system, said first and second polar coordinate systems being angularly offset relative to each other a predetermined angle.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic plan view of one embodiment of an apparatus according to the invention;

and IR which serve as type of a film magazine or FIG. 2 is a diagrammatic elevation showing a portion of the apparatus according to FIG. 1;

FIG. 3 is an elevation of an arrangement including the apparatus illustrated by FIGS. 1 and 2, so as to show the practical use of the arrangement;

FIG. 4 is a diagrammatic plan view of a situation at sea involving two practicing vessels and illustrates the system of gun firing practice and its observation;

FIGS. 5a and 5b represent by Way of example photographs taken of two different images furnished by the cooperating portions of the apparatus according to FIGS. 1-3; and

FIG. 6 illustrates the result of a superimposition of two images like those represented by FIGS. 5a and 5b.

As can be seen from FIG. 1, the apparatus according to the illustrated embodiment of the invention consists essentially of two conventional photo-theodolites 1L optical observation and surveying instruments. The two instruments 1L and 1R are mounted in fixed relation to each other on a common platform 2 which, as will be explained later, is permanently kept in horizontal position. It is of importance, that the instruments 1L and IR are so mounted in a fixed relation to each other that the main optical or directional axes 10L and 10R are angularly offset horizontally and laterally a predetermined angle, preferably 60 as illustrated. Moreover, the instruments 1L and IR are so arranged that their optical axes 10L and 10R always in clude an identical angle of elevation with respect to the horizontal platform 2. In the illustrated example the axes 10L and 10R are both parallel with the horizontal platform 2. The photographic portion of the photo-theodolites may comprise a tiltable mirror 11 as Well known from certain types of photographic cameras, and some film holder 12, preferably of the type known by the trade name Polaroid which permit the immediate development of a taken picture within the camera. The tubes 14 carry the objectives while extensions 13L and 13R constitute the ocular system of the arrangement. It is easy to understand that the light rays entering the objectives from the front are guided and mirrored through the apparatus so as to furnish at the oculars images representing the fields of view pertaining to the two instruments. Conventional means (FIGS. a, 5b) well known to the art include cross-hairs which will appear in the images delivered by the oculars, and which also would appear in photographs taken by the instruments. The intersection of the cross-hairs would always correspond to the optical axis of the particular instrument. Conventionally, the horizontal cross-hair is provided with a graduation representing selected angular distances from the center point 'e.g., preferably in accordance with the well known system of measuring such angles in units called mil. As can be seen further from FIGS. 5a and 5b it is conventional to equip apparatus of this kind with means for showing on the photographic picture also which focal distance has been used when different telephoto lenses 14 are used. In addi tion it would be desirable to provide in the same manner the individual pictures with an indication L or R for showing from which one of the instruments the picture is obtained, and if possible also a sequential number of the picture and an indication of the range or distance of the imaginary target from the gun position as'will be explained further below. It would be particularly advantageous if both cameras are provided with synchronized rewinding and with a common shutter release device as indicated diagrammatically at 33' in FIG. 3.

As can be seen from FIG. 3 the specific arrangement according to the invention may constitute part of a comprehensive training apparatus. Accordingly, a supporting column 30 may be mounted in a fixed position on the deck 3 of a ship and may include a seat for an observer or operator B. A conventional gyro system 31 is provided for maintaining, via a gimbal system contained in a bellows 32, the base plate 2 always in horizontal position irrespective of the movements of the deck 3. Elevation and azimuth adjustments of the base plate 2 and the instrument carried thereby may be effected by the observer or operator B by means of the control handle 33.

While in FIGS. l-3 the photographic camera system has been illustrated only diagrammatically in its simplest form, with an individual film magazine 12 associated with each optical system 1L and IR, respectively, it is obvious that in a well known manner the photographic camera system, could be modified in such a manner that the two individual images furnished by the two different objectives are superimposed upon each other directly within the photographic camera system and reproduced on one single film.

FIG. 4 will illustrate how in a preferred manner gun firing practice involving two vessels at sea can be carried out with the aid of the method and apparatus according to the invention. It may be assumed that two vessels S1 and S2 participate in joint gun firing practice. Theoretically they fight each other and may behave like under ordinary battle conditions i.e. each of these vessels may follow its own course k1 and k2, respectively, at any desired speeds. On each of the two vessels conventional firing control devices are used for determining the firing data which have to be computed in order to hit the other vessel. However, the gun control is modified in both cases i.e., on each of the two vessels, so that automatically the gun to be fired is aimed at an imaginary target point located in an imaginary target direction oifset horizontally and laterally a predetermined angle in one predetermined sense with respect to the line of sight from the gun position to the other vessel which constitutes the theoretical practice target. Preferably the angle between the just mentioned line of sight and the imaginary target direction is 60 in positive or negative sense i.e. toward he is observing at that moment.

the right or toward the left, respectively, as shown in FIG. 4. Since the guns are in either case set for shooting a distance D from the one vessel to the other one, the imaginary target point P is located at the distance D from either one of the vessels S1 and S2 and of cours in the above mentioned imaginary target direction. In the preferred situation as illustrated the imaginary target point P and the location of the two ships S1 and S2 determine an equilateral triangle located at sea level.

It may be assumed that the two ships fire alternatingly. Each of the two ships is equipped with an apparatus according to the invention as illustrated in FIGS. 1-3. On both ships the optical axis of one of the two optical systems, 10L or 10R, as the case may be, is oriented by the respective observer B toward the other vessel so that the image of the latter will appear at the cross-hairs intersection in the particular instrument. In view of the construction of the apparatus according to the invention the respective other optical system is bound to be oriented in the respective imaginary target direction.

Upon firing a projectile the observer will perceive in his ocularsystem 13 a situation as illustrated by FIG. 6 because in his brain the two individual images as illustrated by FIGS. 5a and 5b superimpose themselves over each other. Consequently, the phantom situation illustrated by FIG. 6 is a substitute for the actual situation that would exist if the respective gun had been aimed and fired directly at the other ship. In the combined picture FIG. 6 a hit as well as a miss T will clearly show in correct relation with respect to the theoretical target point. The horizontal line of the cross-hairs system is provided with the conventional graduation in mils; and error angle AOL can be read directly from this graduation. This is even possible if the intersection of the cross-hairs system is not in register with the target ship or a selected portion of the target ship.

The moment the observer B observes the splash of a miss T, or in certain cases a direct hit, he would operate the shutter release button 33' in order to produce a photographic record of the situation he has observed or Immediately thereafter he willtake care of making the photographic equipment ready for another picture taking. It is well known that in the case of using two cameras of the so-called Polaroid type already'after about 10 seconds photographic pictures according to FIGS. 5a and 5b could be obtained from the cameras. Since both pictures carry the same picture number and an indication of the focal length of the objective used in the process and preferably also an indication of the distance or range D, the two separate pictures according to FIGS. 5a and 5b may be easily evaluated particularly since also an existing error angle Ana is shown on one of the pictures. In the case of a modified photographic camera system as mentioned above only one picture according to FIG. 6 would be furnished which however could be evaluated in exactly the same manner. In any case, the observation made by the observer B and recorded by means of photographic pictures rnost satisfactorily serves the purposes of the gun firing practice because the accuracy of the firing data computation and of all other factors involved can be ascertained.

It can be seen from the above that the method and apparatus according to the invention makes it possible to carry out gun firing practice, particularly at sea, under conditions which are more closely similar to battle conditions and yet in a manner which eliminates the necessity of towing a practice target through the practice area.

It Will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of a method and apparatus for carrying out observation at gun firing practice involving a target practice object differing from the types described above.

While the invention has been illustrated and described as embodied in a method and apparatus for carrying out observation at gun firing practice involving a target practice object by means of simultaneous observation of an actual practice target and an imaginary practice target, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can i by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A surveying apparatus, comprising, in combination, a first surveying means for furnishing directional data of a first remote object in terms of polar coordinates in a first polar coordinate system; a second surveying means for furnishing directional data of a second remote object in terms of polar coordinates in a second polar coordinate system, said first and second polar coordinate systems being angularly offset relative to each other a predetermined angle and having a common pole; and optical means in the region of said pole for producing superimposed images of said remote first and second objects.

2. A surveying apparatus, comprising, in combination, a first surveying means for furnishing directional data of a remote object in terms of polar coordinates in a first polar coordinate system and having a first main directional axis; and a second surveying means for furnishing directional data of a remote object in terms of polar coordinates in a second polar coordinate system and having a second main directional axis, said first and second polar coordinate systems having a common point of origin and having a horizontal reference plane in common extending through said point of origin, said first and second main directional axes being offset relative to each other a predetermined, angle and having always the same elevational angle relative to said horizontal plane; and a pair of oculars located near said point of origin in said first and second main directional axes and having axes coinciding with the same, respectively, for producmg superimposed images of said remote objects.

3. A surveying apparatus, comprising, in combination, a first optical observation means for furnishing directional data of a remote object in terms of polar coordinates in a first polar coordinate system and having a first main direction axis; and a second optical observation means for furnishing directional data of a remote object in terms of polar coordinates in a second polar coordinate system and having a second main directional axis, said first and second polar coordinate systems having a common point of origin and having a horizontal reference plane in common extending through said point of origin, said first and second main directional axes being ofiset relative to each other a predetermined angle and having always the same elevational angle relative to said horizontal plane, each of said first and second optical observation means including an ocular system, said ocular systems being spaced and positioned in said first and second main directional axes for producing, respectively, a first virtual image corresponding to the field of view of said first optical observation means and a second virtual image corresponding to the field of view of said second optical observation means superimposed upon said first virtual image.

4. A target practice apparatus comprising a first optical observation means having a first axis, and a second optical observation means having a second axis located in a common plane with said first axis intersecting the same at a point of intersection, and defining a selected angle with the same, said first and second optical observation means respectively including first and second ocular means located in said first and second axes, respectively, for producing superimposed images of first and second remote areas at which said first and second optical observation means are simultaneously directed; and means for simultaneously turning said first and second optical observation means in said plane for observing through said first optical observation means a specific target practice object in said first remote area whereby the image of a projectile in said second remote area is superimposed on the image of said specific target practice object.

5. An apparatus as claimed in claim 4, wherein said first and second optical observation means are phototheodolites.

6. An apparatus as claimed in chr-onized shutter release means lites.

7. An apparatus as claimed in claim 4, wherein said photo-theodolites are so combined structurally and operatively that upon actuation a photographic picture is obtained showing said images in superposition.

8. The combination of a first movable craft with a target practice apparatus according to claim 4 supported thereon, and with a second craft forming said target practice object.

9. Method of gun firing practice involving a real practice target located spaced from a gun station in a real target direction which changes if the position of the real practice target or of a gun at said gun station changes, comprising the steps of aiming at the gun station an aiming device at said real practice target along an aiming line intended to coincide with the real target direction in which the target is located at the moment of aiming; determining from the result of said aiming the determined aiming direction of said real practice target at the moment of impact of a projectile fired by said gun; firing a gun at said gun station in a direction offset by a predetermined angle from said determined aiming direction; and observing images of the area in which said real practice target is located and of the area at which said gun is fired, said images being taken from said gun station along viewing lines enclosing said predetermined angle and being superimposed upon each other so as to show the location of the impact of a projectile fired by said gun relative to said real practice target as if said projectile had been fired at said real practice target proper.

10. Method of gun firing practice according to claim 9 wherein the gun at said gun station is fired in a direction offset by 60 from said determined aiming direction and wherein said images are taken from said gun station along viewing lines including also an angle of 6 11. Method of gun firing practice according to claim 9 wherein said gun station is located aboard a vessel at sea.

12. Method of wherein said real sel at sea.

13. Method of gun firing practice according to claim 9 wherein said real practice target is located aboard a vessel at sea and said gun station is located aboard another vessel at sea spaced from said first vessel at sea.

14. A gun firing practice arrangement comprising in combination, a practice gun station including a practice gun; a real practice target located spaced from said practice gun station in a real target direction which changes 1f the position of said real practice target or of said gun at said practice gun station changes; an aiming device located at said gun station; means for aiming said aiming device along an aiming line intending to coincide with the real target direction in which the target is located at the moment of aiming; means for determining from the result of said aiming the determined aiming direction of said real practice target at the moment of impact of a projectile fired by said practice gun; means for firing claim 4, including synfor said photo-theodogun firing practice according to claim 9 practice target is located aboard a ves- 7 )3 said practice gun at said practice gun station in a direc- References Cited by the Examiner 231125 325525 32 2??? iaiii fii 53$ gfiifififii UNITED STATES PATENTS 1 1 l 1 e s i 1 images of the area in which said real practice target is 2 7/1208 Chaboty 8823 located and of the area at which said gun is fired; means 5 9/8765 7/1/11 3366 for superimposing said images; and means for observing 1297323 5/1218 Kleldman said images, said thus observed images showing the loca- 2,531,400 11/150 Clarkson 35 25 2,893,123 7/1959 Bach 951.1 X

tion of the impact of a projectile fired by said practice gun relative to said real practice target as if said projectile had been fired at said real practice target proper. 10 JOHN HORAN Pfimmy Examiner 

1. A SURVEYING APPARATUS, COMPRISING, IN COMBINATION, A FIRST SURVEYING MEANS FOR FURNISHING DIRECTIONAL DATA OF A FIRST REMOTE OBJECT IN TERMS OF POLAR COORDINATES IN A FIRST POLAR COORDINATE SYSTEM; A SECOND SURVEYING MEANS FOR FURNISHING DIRECTIONAL DATA OF A SECOND REMOTE OBJECT IN TERMS OF POLAR COORDINATES IN A SECOND POLAR COORDINATE SYSTEM, SAID FIRST AND SECOND POLAR COORDINATE SYSTEMS BEING ANGULARLY OFFSET RELATIVE TO EACH OTHER A PREDETERMINED ANGLE AND HAVING A COMMON POLE; AND OPTICAL MEANS IN THE REGION OF SAID POLE FOR PRODUCING SUPERIMPOSED IMAGES OF SAID REMOTE FIRST AND SECOND OBJECTS. 